NEW DITERPENE ISOPIMARA-7,15-DIEN-19-OIC ACID AND ITS PROLYL ENDOPEPTIDASE INHIBITORY ACTIVITY.

The ethanolic extract of the bulbs of Fritillaria imperialis was subjected to fractionation by solvent-solvent extraction. The nonpolar fraction showed inhibitory activity against prolyl endopeptidase (PEP) (EC.3.4.21.26). a large intracellular enzyme that preferentially hydrolyze proline-containing oligopcptidase at the carboxylic side of a prolyl residue. We have isolated a diterpenoid isopimara-7.15-dien-19-oic acid (1) from the nonpolar fraction of F. imperial is and on methylation of compound 1. a methylester 2 was obtained which is a known compound previously isolated from Fritillaria thunbergii. The present article describes the isolation and structural elucidation of isopimara-7,l5-dien-19-oic acid (1) by single-crystal Xray diffraction techniques along with its prolyl endopeptidase inhibitory activity. [ABSTRACT FROM AUTHOR]